textproduct: Quad Cities

KEY MESSAGES

- A prolonged period of hot and very humid conditions really gets established today, highlighted by day-to-day peak heat index values of 100 to 110 and nighttime low temperatures no cooler than the mid 70s. The Extreme Heat Warning has now been extended through Wednesday evening.

- Thunderstorm chances will be limited through midweek, with increasing chances Wednesday night onward (including the July 4th weekend), with the resultant cloud cover potentially having an impact on how high temperatures can get, but at least it will remain very humid.

SHORT TERM /THROUGH TONIGHT/

Issued at 235 AM CDT Mon Jun 29 2026

It's muggier than a dog's mouth out there this morning, and that's going to be the daily story this week. Upper air analysis shows that the robust upper ridge axis is along and just east of the mid to upper MS RVR Valley will edge off slightly to the east today acrs the western GRT LKS and OH RVR Valley. This while western flank southwesterlies stay active from the deep southwestern plains to the upper MS RVR Valley/NW GRT LKS. Mass field placement and warm frontal progression suggest the local area to be under the influence of a breezy full on warm sector today, with mixing profiles supporting widespread highs in the low to mid 90s(as long as we get adequate insolation) and mid 70 sfc DPTs. This will make for max heat index readings in the 104 to 108 degree range this afternoon and supportive of the ongoing extreme heat headlines. Lingering upper ridge effect and fcst soundings sporting a stout EML acrs the area(H7 MB temps 13-15C)should keep the area precip free and deflected off to the west and north. BUFKIT mixing depth suggests afternoon wind gusts will range 30 to 35 MPH and may keep a bit of a lid on sfc DPTs climbing higher than the mid 70s.

Tonight, more of the same with breezy south winds and high DPTs keeping low temps from dipping much below the mid to upper 70s and possibly some areas not making it lower than 80. Ridging and EML keeping the local area precip-free and the storm clusters occurring more out acrs the MO RVR Valley into MN through Tue morning.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 235 AM CDT Mon Jun 29 2026

Tuesday...Ongoing EML and more prime storm track/Ring of Fire remaining west and north of the DVN CWA, another hot breezy day with heat index's of 105-110 degrees. Vertical thermal profiles and H85 temps support high temps in the upper 90s to low 100s, but the ambient high humidity should keep a lid on the high temps having trouble warming past the mid 90s. Accepted CAMs and most deterministic ensembles keep the dry tend going through Wed morning, while interestingly the 00z ECMWF has showers and storms making it acrs the north half of the CWA Tue morning. Will keep the fcst mainly dry. Extreme Heat Warning continues.

Wednesday...Medium range ensembles and upper jet progs suggest the active southwesterlies edge closer to the western and northern side of the DVN CWA this day, but besides maybe some decaying debris spilling in acrs the west and north at times, feel the EML and lingering ridge centered off acrs the OH RVR Valley will maintain the mainly precip free regime for one more day at least. Thus with low to mid 90s still fcst with the ongoing high humidity, have extended the Extreme Heat Warning acrs the entire area through Wed evening. Wednesday night into Thu morning is when upstream storm clusters may have a better chance to bleed down or in from the west into portions of the local area.

Thursday through Sunday...For this time period, confidence is high in continued very humid air especially through Saturday. However, convective effects may influence temperatures as the upper pattern flattens a bit over the Upper Midwest and Corn Belt. Using ensemble means and deterministic guidance, the current best convective potential looks to be over the weekend as a short wave trough approaches. That said, predictability at this distance is low, and some noteworthy shifting such as MCS effects prior or a change in trough passage timing certainly can occur. Otherwise, synoptically the pattern of 850 mb temperatures of 20-22C support high temperatures at least in the lower 90s, which would mean heat index values into the 100+ range, and potentially 105-110.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1235 AM CDT Mon Jun 29 2026

Some lower VFR level stratocu will continue just north of CID and acrs DBQ into Monday morning before moving on. Otherwise south to southeasterly sfc winds of 10-15 KTs overnight will increase by mid to late Monday morning to 15-25 KTs for another breezy day. If the sfc winds decrease to around 10 KTs by mid Monday evening, there may be some marginal LLVL wind shear acrs a few of the sites with a southwesterly LLJ of 40-45 KTs.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Extreme Heat Warning from noon today to 10 PM CDT Wednesday for IAZ040>042-051>054-066. Extreme Heat Warning until 10 PM CDT Wednesday for IAZ063>065- 067-068-076>078-087>089-098-099. IL...Extreme Heat Warning from noon today to 10 PM CDT Wednesday for ILZ001-002-007-009-016>018. Extreme Heat Warning until 10 PM CDT Wednesday for ILZ015- 024>026-034-035. MO...Extreme Heat Warning until 10 PM CDT Wednesday for MOZ009-010.